Method openFromStreamImpl

src/SFML/Graphics/Font.cpp:454–517

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bool Font::openFromStreamImpl(InputStream& stream, std::string_view type)
{
    // Cleanup the previous resources
    cleanup();

    auto fontHandles = std::make_shared<FontHandles>();

    // Initialize FreeType
    // Note: we initialize FreeType for every font instance in order to avoid having a single
    // global manager that would create a lot of issues regarding creation and destruction order.
    if (FT_Init_FreeType(&fontHandles->library) != 0)
    {
        err() << "Failed to load font from " << type << " (failed to initialize FreeType)" << std::endl;
        return false;
    }

    // Prepare a wrapper for our stream, that we'll pass to FreeType callbacks
    fontHandles->streamRec.base               = nullptr;
    fontHandles->streamRec.size               = static_cast<unsigned long>(stream.getSize().value());
    fontHandles->streamRec.pos                = 0;
    fontHandles->streamRec.descriptor.pointer = &stream;
    fontHandles->streamRec.read               = &read;
    fontHandles->streamRec.close              = &close;

    // Setup the FreeType callbacks that will read our stream
    FT_Open_Args args;
    args.flags  = FT_OPEN_STREAM;
    args.stream = &fontHandles->streamRec;
    args.driver = nullptr;

    // Load the new font face from the specified stream
    FT_Face face = nullptr;
    if (FT_Open_Face(fontHandles->library, &args, 0, &face) != 0)
    {
        err() << "Failed to load font from " << type << " (failed to create the font face)" << std::endl;
        return false;
    }
    fontHandles->face = face;

    // Load the stroker that will be used to outline the font
    if (FT_Stroker_New(fontHandles->library, &fontHandles->stroker) != 0)
    {
        err() << "Failed to load font from " << type << " (failed to create the stroker)" << std::endl;
        return false;
    }

    // Select the Unicode character map
    if (FT_Select_Charmap(face, FT_ENCODING_UNICODE) != 0)
    {
        err() << "Failed to load font from " << type << " (failed to set the Unicode character set)" << std::endl;
        return false;
    }

    // Store the loaded font handles
    m_fontHandles = std::move(fontHandles);

    // Store the font information
    m_info.id                 = getUniqueId();